Robots are automated, autonomous, or remotely-operated devices that are able to manipulate objects using a series of links, which in turn are interconnected via articulations or motor-driven robotic joints. Each joint in a typical robot represents an independent control variable, also referred to as a degree of freedom (DOF). End-effectors are the links used for performing a task at hand, e.g., grasping a work tool or an object. Therefore, precise control of a robot may be organized by the level of task specification: object level control, i.e., the ability to control the behavior of an object held in a single or cooperative grasp of a robot, end-effector control, and joint control. Collectively, the various control areas cooperate to achieve the required functionality.
Humanoid robots in particular are configured with an approximately human structure, functionality, and/or appearance, whether a full body, a torso, and/or an appendage, with the structural complexity of the humanoid robot being largely dependent upon the nature of the work task being performed. The use of humanoid robots may be preferred where direct interaction is required with devices or systems that are specifically made for human use. Due to the wide spectrum of work tasks that may be expected of a humanoid robot, different control modes may be simultaneously required. For example, precise position control must be applied within the different spaces noted above, as well as control over the applied torque or force, motion, and the various grasp types.
Robot control architectures typically provide only low-level diagnostic information, such as threshold-based fault detection and isolation. Such post-fault detection and isolation approaches are used mainly during system deployment or fault recovery modes, and therefore may provide a less than optimal approach to Integrated Life Cycle Management. Likewise, the high cost of scaling and integrating new control functionality into an extremely complex electro-mechanical system such as the 42+ DOF humanoid robot described herein may pose especially problematic system development and interfacing issues.